fnResize()
window.onresize = function () {
fnResize()
}
function fnResize() {
var deviceWidth = document.documentElement.clientWidth || window.innerWidth
if (deviceWidth >= 750) {
deviceWidth = 750
}
if (deviceWidth <= 320) {
deviceWidth = 320
}
document.documentElement.style.fontSize = (deviceWidth / 7.5*2) + 'px'
}